The present invention relates generally to disk drives, and more specifically to techniques for providing power to the motors in a disk drive. Most of the discussion will concentrate on the example of hard disk drives (HHDs).
One problem facing system integrators who design systems consisting of hard disk drives (HDDs) is to design power supplies capable of meeting both peak and average load conditions. In systems containing many HDDs, the differences between these conditions can become quite large, especially when considering that many drives may be simultaneously acting under their peak load conditions. Considerable cost may go into those system supplies in order to maintain reliable operation well beyond the statistical average load. Minimizing the difference between peak and average load currents eases design requirements for such system power supplies.
Additionally, the peak load from the perspective of the mechanics of the HDD involves increased seek duty cycles (more movement from the head actuators while disk rotation is maintained at its normal operating point). Seeking is necessary in order to allow quick, random access to data stored on the magnetic disk(s). A second problem then is the design tradeoff in the electromechanical system that is made to compromise power consumption for improved access time. The industry demands continued performance improvements as well as energy efficiency. Enabling such advances in HDDs allows new products to work in legacy systems without power supply upgrades.
This design tradeoff may relate to a third problem of limited battery life for mobile applications. Improvements in mobile HDD operating efficiency may translate directly to extended battery life for a given application.